Use Outlook Copilot to Summarize Project Email Threads

What This Does

Outlook's Copilot reads an entire email thread and produces a one-paragraph summary with key decisions made and open questions — turning a 40-email chain into a 30-second catch-up. Essential for project managers returning from PTO or trying to find what was decided in a buried thread.

Before You Start

• You have Microsoft 365 with Copilot enabled (requires M365 Business Standard or Copilot add-on)
• You're using Outlook for Microsoft 365 (desktop app or web at outlook.office.com)
• The email thread you want to summarize is in your mailbox

Steps

1. Open the email thread

Click on the email thread you want to summarize. It can be any length — Copilot handles even very long chains. You'll see the thread expanded with all messages.

2. Find the Copilot Summary button

At the top of the email thread (just above the first message), look for the Copilot button or a Summarize banner. In the web version of Outlook, it appears as a small colored banner that says "Summarize this thread by Copilot." In the desktop app, look for the Copilot icon in the email reading pane toolbar.

What you should see: A "Summarize" prompt or Copilot icon above the email messages.

3. Click Summarize

Click the button. Copilot reads the entire thread and generates a summary in about 10–20 seconds. The summary appears in a collapsible panel above the email thread.

The summary typically includes:

• What the thread is about (1–2 sentences)
• Key decisions or outcomes
• Who is responsible for next steps (when clearly stated in the thread)
• Open questions or unresolved items

4. Use Copilot to ask follow-up questions

In the Copilot pane, you can type questions: "What did Sarah agree to do?" or "Has a decision been made about the go-live date?" — Copilot searches the thread and answers directly.

What you should see: Direct answers pulled from the email text, often with quotes from specific messages.

Troubleshooting: If the Summarize button doesn't appear, your M365 plan may not have Copilot enabled. Ask your IT admin to confirm. If threads from external senders aren't summarizing correctly, Copilot may not have access to reply-all threads — try with internal-only threads first.

5. Draft a reply using Copilot

Still in the thread, click Reply then look for the Copilot button in the reply compose toolbar. Tell it: "Draft a reply confirming the decisions made in this thread and listing the agreed next steps with owners and dates." Copilot drafts the reply based on the thread content.

Real Example

Scenario: You return from a 3-day conference to find a 32-email thread about a scope change discussion that happened while you were out. You need to understand what was decided before your 10am call.

What you do: Open the thread. Click Summarize. Read the 4-sentence summary.

What you get: "During your absence, the team discussed expanding the project scope to include Phase 2 data migration. Marcus and the business analyst agreed to a preliminary estimate by Wednesday. The client requested this be added to the next steering committee agenda. No formal change request has been submitted yet."

Time saved: Finding the key decisions in a 32-email thread took 8 minutes manually; Copilot summarizes it in 15 seconds.

Tips

• Use it for every catch-up: Make summarizing email threads your default first step when coming back to a project discussion. It takes 15 seconds and saves you from reading every message.
• Ask about decisions vs. discussions: Type "What decisions were made vs. what's still being discussed?" — Copilot distinguishes between resolved and open items, which is exactly what you need to know before a meeting.
• Summarize before you reply-all: Before adding your response to a long thread, summarize it first — you'll avoid duplicating what's already been said.

Tool interfaces change — if a button has moved, look for similar AI/magic/smart options in the same menu area.